On Aug. 11, 1999, President Bill Clinton awards the Presidential Medal of Freedom, the nation's highest civilian honor, to Edgar M. Bronfman at a ceremony held in the East Room of the White House. (Pablo Martinez Monsivais/AP)

Edgar M. Bronfman Sr., a billionaire businessman and longtime president of the World Jewish Congress, which lobbied the Soviets to allow Jews to emigrate and helped spearhead the search for hidden Nazi loot, died Dec. 21 at his home in New York. He was 84.

His family charity, the Samuel Bronfman Foundation, announced the death but did not disclose the cause.

The hard-driving and mercurial Bronfman made his fortune with his family’s Seagram liquor empire, taking over as chairman and chief executive in 1971 and continuing the work of his father, Samuel. Under Edgar Bronfman’s leadership, Seagram expanded its offerings and was eventually acquired by French media and telecom group Vivendi Universal in 2000.

Mr. Bronfman’s wealth, combined with his role in the World Jewish Congress, an umbrella group of Jewish organizations in some 80 countries that he led for more than a quarter century, allowed him to be a tireless advocate for his fellow Jews.

In 1999, President Bill Clinton awarded Mr. Bronfman the Presidential Medal of Freedom, the nation’s highest civilian honor. In the citation, Mr. Bronfman was heralded for working “to ensure basic rights for Jews around the world.”

In a 1986 Associated Press profile, he said his position and money helped him have access to world leaders.

“It’s a combination of the two,” Mr. Bronfman said. “In the end, it doesn’t really matter why that access is available, as long as it is there.”

The year before, he had become the first WJC president to meet with Soviet officials in Moscow, bringing his case for human rights and taking a little time to promote Seagram’s interests. He visited again in 1988, by which time Jewish emigration from the Soviet Union, a key goal of the congress, had begun to rise under the reforming leadership of Mikhail Gorbachev.

During the 1980s and 1990s, the WJC also helped lead the effort to gain $11 billion in restitution for heirs of Holocaust victims.

Jews in Germany and Nazi-held countries were stripped of their possessions, their artworks and even the gold fillings from their teeth in the regime’s death camps. Much of the gold wound up in Swiss banks, and the institutions came under heavy criticism decades after the war ended for failing to make adequate reparations.

In 1975, the Bronfman family made the news for a far different reason when one of Edgar Bronfman’s sons, 21-year-old Samuel II, was abducted in a New York suburb.

The family paid a $2.3 million ransom, and Samuel was later found when authorities raided a Brooklyn apartment. The missing money was found under a bed and two men were arrested.

The two were convicted of extortion but acquitted of kidnapping in a sensational 1976 trial in which the defense accused Samuel Bronfman of staging his own kidnapping as a hoax intended to cheat his father out of the ransom money. Samuel Bronfman denied the allegation, and the prosecution called it “ridiculous.”

The family business had been built in Canada by Mr. Bronfman’s father, who entered the liquor business in 1915. His company, Distillers Corp., bought out rival Joseph E. Seagram & Sons in 1928. During that same period, when Prohibition was enforced in the United States, much of their product sold legally in Canada later found its way into the bootleg U.S. market.

During Samuel Bronfman’s tenure, New York’s Seagram Building became an important architectural landmark. Meanwhile, Edgar Bronfman was running the distilling company’s U.S. operations, and his younger brother, Charles, was president of the Canadian branch.

Samuel Bronfman was one of the world’s richest men by the time he died in 1971, holding investments in real estate, oil and other concerns and donating millions to Jewish causes.

Edgar Bronfman’s son Edgar Jr. helped steer Seagram into the entertainment business in the 1990s. Seagram took over MCA, with its big movie, music and theme park businesses, in 1995, and Edgar Jr. became an executive with Vivendi after a 2000 deal.

Vivendi’s expansion efforts later ran into financial trouble, and former top executives, including the younger Bronfman, were accused of misleading investors about the company’s health. In 2009, a French judge ordered former Vivendi chief executive Jean-Marie Messier and others to stand trial, including Edgar Bronf­man Jr.

Mr. Bronfman had left the WJC president’s post amid a series of controversies. He had fired his longtime deputy, Rabbi Israel Singer, after a 2006 report by the New York attorney general concluded that Singer improperly used WJC funds for personal use. No criminal charges were filed.

Edgar Miles Bronfman was born in Montreal on June 20, 1929. Because of the family fortunes, he was raised amid luxury during the Depression, but in his memoir, “Good Spirits,” he described a home life of “emotional dysfunction,” with a distant mother and a father preoccupied by work. After attending boarding schools, he graduated in 1951 from McGill University in Montreal and joined the family business.

In 1953, he married Ann Loeb, an heiress of two Wall Street investment banking families. Their marriage led to many business ventures, with the Bronfmans using the Loeb, Rhoades & Co. investment firm to buy swaths of land and diversify its holdings into the entertainment and petroleum industries.Edgar and Ann Bronfman divorced in 1973.

In 1973, Edgar Bronfman married Lady Carolyn Townshend, but the union lasted only a year. Subsequently, he twice married and divorced Rita Webb, who went by Georgiana.

Survivors include his wife, Jan Aronson, an artist; five children from his first marriage; two daughters from his second marriage; a brother; a sister; 24 grandchildren; and two great-grandchildren.

— From staff and wire reports